Could not complete sign-in with the provider
The site could not exchange the OAuth authorization code for a profile (wrong secret, expired code, redirect URI mismatch, or provider API error).
Why this happens
Most specific social-login failure at exchangeCodeForProfile. Distinct from “could not complete sign-in” after a successful exchange.
Diagnose and fix
1. Admin: Settings → Mods → Social login — verify app id/secret for that provider.
2. Match OAuth redirect URI exactly in the provider console.
3. Confirm PUBLIC_APP_URL / site URL is correct (https, no trailing-path typos).
4. Retry once; codes expire quickly if the user delayed.